src/include: Add space before (

Fix the following error detected by checkpatch.py:

ERROR: space required before the open parenthesis '('

TEST=Build and run on Galileo Gen2

Change-Id: I6969e63f750f327afff1a0efa1aab56d477af0df
Signed-off-by: Lee Leahy <Leroy.P.Leahy@intel.com>
Reviewed-on: https://review.coreboot.org/18645
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/include/bootstate.h

@@ -150,7 +150,7 @@ struct boot_state_callback {
 		INIT_BOOT_STATE_CALLBACK_DEBUG(bscb_)	\
 		bscb_->callback = func_;		\
 		bscb_->arg = arg_			\
-	} while(0)
+	} while (0)
 
 /* The following 2 functions schedule a callback to be called on entry/exit
  * to a given state. Note that there are no ordering guarantees between the